1. Field of the Invention
The present invention relates to an endoscope cooling device to be attached at an insertion portion of an endoscope for observing a test substance and to an endoscope system including the endoscope cooling device and the endoscope.
2. Description of Related Art
Conventionally, there has been used an endoscope having an insertion portion, which can be inserted into a test substance in order to make observable a narrowed part such as a duct for which an observer is, otherwise, unable to make a direct visual observation (for example, refer to Japanese Unexamined Patent Application, First Publication No. 2005-342010). An observation portion such as a solid-state image sensor (for example, a CCD) is disposed at the distal end of an insertion portion of the endoscope, thus making it possible to observe a test substance in the vicinity of the distal end of the insertion portion. Further, an illuminating means is installed at the distal end of the insertion portion, thus making it possible to illuminate the vicinity of the distal end of the insertion portion and preferably observe the test substance.
In this instance, since the insertion portion of the endoscope is provided as described above at the distal end with an observation portion such as a solid-state image sensor (for example, a CCD) and an illuminating means, it is restricted to a maximum allowable working temperature of up to about 80° C., in relation to heat-resistant temperatures of these devices taken into account. As a result, when the endoscope is used as an industrial endoscope in an attempt to observe the interior of an engine, the structure of which is complicated, it is impossible to make an observation as it is with the insertion portion inserted therein because the temperatures are raised to 200° C. or higher at completion of operation. Thus, the endoscope finds limited application. Therefore, an industrial endoscope has been proposed, which allows an operator to make an observation under the above high-temperature environment (for example, refer to Japanese Unexamined Patent Application, First Publication No. 2000-46482).
The industrial endoscope disclosed in the document (Japanese Unexamined Patent Application, First Publication No. 2000-46482) is provided with an inner flexible body, an insertion portion having an outer flexible body installed by forming a space for flowing a fluid between itself and the inner flexible body, an outer casing fixed to the proximal end of the outer flexible body, the interior of which is communicatively connected to a space in which the fluid flows, and a valve fixed to the outer casing and allowing the fluid to flow into the outer casing. Then, the valve is connected to a fluid supply device for supplying a cooling fluid by using a supply duct, thus allowing the cooling fluid to flow, by which the cooling fluid is released from the distal end from the interior of the outer casing through a space between the inner flexible body and the outer flexible body. Thus, the endoscope can be used at high temperatures due to cooling by the cooling fluid.